A device for monitoring a remaining battery capacity of an assembled battery (hereinafter also referred to simply as a “battery”) having a plurality of battery cells connected in series and/or in parallel by detecting a voltage of each battery cell has been available (see, for example, Japanese Unexamined Patent Application Publication No. 8-339829).
However, since such a monitoring device is a low-voltage device, the monitoring device is connected to a high-voltage battery through a capacitor. Therefore, a capacitor is required in a circuit for monitoring the battery, which prevents the reduction in size of the battery.
In particular, as in an assembled battery, an increase in the number of battery cells requires a large number of capacitors, and there is a concern about the increase in occupied volume of the battery cells.